New Colecovision schematics

[Shawn]

You're welcome. Now I'm 99% sure the schematics are correct, after highlighting each net in the PCB program and testing them with the multimeter. The remaining 1% is the pins that appear to be unconnected, but could indeed be hiding traces underneath the chip. But I'm pretty sure I got all the traces.

 

Too bad you can't be sure on those last few pins as it would be awesome to get a new colecovision motherboard printed.

[ChildOfCv]

I was talking specifically about the Expansion 1 there. The CV console board itself is probably complete.

 

Hehe, well it might be fun to find out how much it would cost too. Printing an Arduino-sized board with the minimum order is about $60, for reference. You can do cheaper from China, though.

 

Edit: Osh Park timed out while trying to parse the Gerbers

 

JLCPCB, though, quoted $50 for 5 of them, including shipping. If they actually came through on that, that's a good price, even for something that might not work.

Edited March 30, 2019 by ChildOfCv

[pmetro]

Thanks for posting, doing a refurb on Colecovision nice to have all the info in one place, great reference when I need it.

[ChildOfCv]

Since I've had some time to learn FreeCAD, and since some people want "beautiful" 3D representations of the PCBs, I started creating the missing 3D models for components.  Oooh, and aaaah for me, okay?

 

[ChildOfCv]

Schematics updated, finally.  I added PAL Rev D schematics.  Besides the difference in video generation, it seems that Coleco played around with the clock generator a bit too.

 

Coleco.zip

[ChildOfCv]

Newest version of the schematics.  (Too bad I can't delete old attachments)

 

It has corrections to the PAL D schematics and has some reorganization to hopefully improve readability.

 

 

Coleco.zip

[Ikrananka]

On 7/25/2021 at 5:24 PM, ChildOfCv said:

Newest version of the schematics.  (Too bad I can't delete old attachments)

 

It has corrections to the PAL D schematics and has some reorganization to hopefully improve readability.

Fantastic - thanks for all your hard work producing these.  Invaluable.

Edited July 30, 2021 by Ikrananka

[atari-dna]

@ChildOfCv So, I've had occasion to tear apart a Colecovision vintage power supply.  The filter caps have terrible ESR and are leaky--in both DC and Electrolyte.  

 

I thought I would reach out as you seem to take pride in documenting this hardware from the engineering perspective.  Would you care to have more photos and a component list to render schematics for the internal PCB of the power supply?

 

Here's a sample photo with the electrolytics and regulator ICs removed.  Let me know if you are interested (or anyone else who may be, for that matter) and I'll try to provide photos and parts identification to render a schematic.

 

In the spirit of this thread, I hope some folks find this useful.

 

 

 

[ChildOfCv]

On 5/11/2023 at 2:54 PM, atari-dna said:

@ChildOfCv So, I've had occasion to tear apart a Colecovision vintage power supply.  The filter caps have terrible ESR and are leaky--in both DC and Electrolyte.  

 

I thought I would reach out as you seem to take pride in documenting this hardware from the engineering perspective.  Would you care to have more photos and a component list to render schematics for the internal PCB of the power supply?

 

Here's a sample photo with the electrolytics and regulator ICs removed.  Let me know if you are interested (or anyone else who may be, for that matter) and I'll try to provide photos and parts identification to render a schematic.

 

In the spirit of this thread, I hope some folks find this useful.

 

 

 

Sure.  It looks like all the traces are on the bottom of the PCB, so that's a lot easier to trace out.  Looks to be a linear power supply.

[atari-dna]

cool

Edited May 18, 2023 by atari-dna

[atari-dna]

On 5/17/2023 at 6:23 AM, ChildOfCv said:

Sure.  It looks like all the traces are on the bottom of the PCB, so that's a lot easier to trace out.  Looks to be a linear power supply.

Okay, glad you're interested.  I'll have the reverse side cleaned up and photographed by this weekend, and post some pictures :0)

[cwilkson]

Weird sockets on that supply board.

What ICs are used?  LM723?  Or some type of quad opamp?

 

 

[atari-dna]

On 5/24/2023 at 2:33 PM, cwilkson said:

Weird sockets on that supply board.

What ICs are used?  LM723?  Or some type of quad opamp?

 

 

The sockets weren't there originally, I added them as part of my rebuild.  The chips are LDO 723 regulators.

[cwilkson]

13 hours ago, atari-dna said:

The sockets weren't there originally, I added them as part of my rebuild.  The chips are LDO 723 regulators.

Got it.  That's very interesting.  I know that the '723 was pretty popular.  It's quite a versatile IC.

It can support linear voltage, linear current regulation, and even temperature regulation.

And I'm pretty sure I used it to control a switcher back in the 90's, based on a Radio Shack app note.

But it seems kind of wasteful in a simple linear regulator vs. a 3-pin regulator.

 

BTW, with a dropout voltage of 3000mV I would never call the '723 a Low Drop Out (LDO) regulator.

No matter what TI marketing wants you to believe.

[atari-dna]

Probably implemented as current limiters

 

there are (3) T0-220 package voltage regulators present in the circuit as well (+12, +5 and -5)

 

[DanBoris]

On 12/3/2018 at 6:40 PM, ChildOfCv said:

Hi all,

 

First post. Hopefully it's a good one.

 

Searching high and low for CV schematics and finding only the same set everywhere, and noting that it's lacking in a few places (and in PDF format instead of a schematic file), I set out to engineer a new schematic myself. I still can't guarantee its total accuracy, of course. But I hope it is.

 

I used Kicad 5 for the project, which is also my first time using the package. So some things may not have been done optimally. Constructive criticism is welcome.

 

.zip'd project archive: https://drive.google.com/open?id=1lVH7_HhNAEBQ5yUY1j8FsJktdYjzmgUc

 

Last I checked, Google Drive thought it couldn't display the preview, but the download button should still work.

 

I am guessing you found the ones I drew a long time ago. I believe I did them in ORCAD and stopped maintaining them when I no longer had access to a working copy of that program. I had always intended to re-draw them but never got around to it. Thanks for the work brining them into a more modern schematics capture tool. 

[+5-11under]

1 hour ago, DanBoris said:

I am guessing you found the ones I drew a long time ago. I believe I did them in ORCAD and stopped maintaining them when I no longer had access to a working copy of that program. I had always intended to re-draw them but never got around to it. Thanks for the work brining them into a more modern schematics capture tool. 

They were still very useful, so thanks for your "early work" on this!